Western river fishing closures expand as record heat endangers trout

Yellowstone National Park closed fishing in parts of the park in July 2024 after warm water temperatures and low river flows pushed trout into stress. That same pressure is spreading across Western rivers, where state wildlife agencies are using closures and daytime fishing limits to keep cold-water species alive as record heat lifts stream temperatures and strips water of oxygen.

A hoot-owl restriction limits fishing during the hottest part of the day, when fish are already sluggish and more likely to die after catch-and-release handling. Colorado Parks and Wildlife has used voluntary afternoon closures on portions of the Animas, San Juan and Dolores rivers, while Montana Fish, Wildlife & Parks has a current waterbody closures page for fishing restrictions across the state.

Officials are treating the moves as emergency conservation. When rivers run low, they warm faster and concentrate pollutants, leaving trout and other aquatic life with less oxygen and less room to recover. Yellowstone later lifted partial restrictions on the Firehole River, reopened fishing without restrictions on select rivers in 2025, and then posted additional parkwide fishing restrictions in 2026 before announcing it would extend the fishing season on three rivers in another 2026 update.

Guides lose bookings when a productive stretch is taken out of play, outfitters sell fewer licenses and flies, bait shops lose walk-in traffic, and local tourism businesses can see peak-summer demand disappear overnight.

Yellowstone’s rules center on native fish conservation goals, and cutthroat trout are the park’s sole native trout.